AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is stored when refrigerant pressure is extremely low (0.1762 MPa (1.8 kgf/cm2, 25 psi) or less) or extremely high (3.0254 MPa (30.9 kgf/cm2, 439 psi) or more). The air conditioner pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the air conditioning amplifier. The air conditioning amplifier converts the signal to pressure according to the sensor characteristics to control the compressor.

Tech Tips

Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be stored if there is no refrigerant in the cycle.

DTC No. DTC Detection Condition Trouble Area
B1423/23

  • An open or short in the air conditioner pressure sensor circuit.

  • Refrigerant pressure on the high pressure side is extremely low or extremely high.

  • Air conditioner pressure sensor

  • Harness and connector

  • Expansion valve (blocked, stuck)

  • Condenser (blocked, deterioration of cooling capacity due to dirt)

  • Cooler dryer (moisture in refrigerant cycle cannot be absorbed)

  • Condenser fan (condenser cannot be cooled down)

  • Air conditioning system (leaks, blocked)

  • Refrigerant pipe line

  • Air conditioning amplifier

WIRING DIAGRAM

A0118ONE11

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

    A0119A6E03
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioner Pressure Sensor)

    1. Disconnect the A26 air conditioner pressure sensor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A26-3 (+) - Body ground Ignition switch ON 4.75 to 5.25 V

    NG

    CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER) Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)

    A0119A6E04
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioner Pressure Sensor)

    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-1 (-) - Body ground Always Below 1 Ω

    2. Reconnect the air conditioner pressure sensor connector.


    NG

    CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER) Click here

    OK

  3. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. A01170AE12
      Text in Illustration
      *1

      Component with harness connected

      (Air Conditioning Amplifier)

      Remove the air conditioning amplifier with its connectors still connected Click here.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D15-9 (PRE) - Body ground

      Ignition switch ON

      A/C switch off

      		 0.70 to 4.69 V

      Tech Tips

      If the measured voltage is not within the normal range, there may be a malfunction in the air conditioning amplifier, air conditioner pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.


    NG

    CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER) Click here

    OK

  4. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Measure the voltage when the following conditions are satisfied.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting Lo
      Blower Speed Hi
      A/C Switch On
      Air inlet control Switch Recirculation
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note


      • If refrigerant pressure on the high pressure side becomes extremely high during the inspection (if the voltage exceeds 4.84 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe operation.

      • It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the problem symptom may recur after a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.


      1. A01170AE12
        Text in Illustration
        *1

        Component with harness connected

        (Air Conditioning Amplifier)

        Measure the voltage according to the value(s) in the table below.

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        D15-9 (PRE) - Body ground

        Ignition switch ON

        A/C switch off

        		 0.70 to 4.69 V
        Result
        Result Proceed to
        OK (When troubleshooting according to DTC output) A
        OK (When troubleshooting according to Problem Symptoms Table) B
        NG C

    B

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    C

    INSPECT COOLING FAN SYSTEM Click here

    A

    REPLACE AIR CONDITIONING AMPLIFIER Click here

  5. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

    A01199HE01
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioner Pressure Sensor)
    *2

    Rear view of wire harness connector

    (to Air Conditioning Amplifier)

    1. Disconnect the D15 air conditioning amplifier connector.

    2. Disconnect the A26 air conditioner pressure sensor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-3 (+) - D15-10 (S5-3) Always Below 1 Ω
      D15-10 (S5-3) - Body ground Always 10 kΩ or higher

    4. Reconnect the air conditioning amplifier connector.

    5. Disconnect the air conditioner pressure sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here

  6. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

    A01199HE02
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioner Pressure Sensor)
    *2

    Rear view of wire harness connector

    (to Air Conditioning Amplifier)

    1. Disconnect the D15 air conditioning amplifier connector.

    2. Disconnect the A26 air conditioner pressure sensor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-1 (-) - D15-13 (SG-2) Always Below 1 Ω
      D15-13 (SG-2) - Body ground Always 10 kΩ or higher

    4. Reconnect the air conditioning amplifier connector.

    5. Reconnect the air conditioner pressure sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here

  7. CHECK HARNESS AND CONNECTOR (PRESSURE SENSOR - AIR CONDITIONING AMPLIFIER)

    A01199HE03
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioner Pressure Sensor)
    *2

    Rear view of wire harness connector

    (to Air Conditioning Amplifier)

    1. Disconnect the D15 air conditioning amplifier connector.

    2. Disconnect the A26 air conditioner pressure sensor connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A26-2 (PR) - D15-9 (PRE) Always Below 1 Ω
      D15-9 (PRE) - Body ground Always 10 kΩ or higher

    4. Reconnect the air conditioning amplifier connector.

    5. Reconnect the air conditioner pressure sensor connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK FOR AIR CONDITIONING SYSTEM LEAK


    1. Install the manifold gauge set.

    2. Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

    3. Evacuate the air conditioning system and check that vacuum can be maintained in it.

      OK
      Vacuum can be maintained in the air conditioning system.

      Tech Tips

      If vacuum cannot be maintained in the air conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the air conditioning system.


    NG

    REPAIR AIR CONDITIONING SYSTEM LEAK Click here

    OK

  9. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  10. RECHECK DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting Lo
      Blower Speed Hi
      A/C Switch On
      Air inlet control Switch Recirculation
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning system operates for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      OK
      DTC B1423 is not output.

      Note

      If the DTC was stored due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks as necessary.


    NG

    INSPECT AIR CONDITIONER PRESSURE SENSOR Click here

    OK

    END

  11. INSPECT AIR CONDITIONER PRESSURE SENSOR

    A011A95E01

    1. Install the manifold gauge set.

    2. Reconnect the A26 air conditioner pressure sensor connector.

    3. Remove the air conditioning amplifier with its connectors still connected Click here.

    4. Turn the ignition switch to ON.

    5. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      D15-9 (PRE) - D15-13 (SG-2)

      Refrigerant pressure:

      Normal pressure (less than 3.0254 MPa [30.9 kgf/cm2, 439 psi] and more than 0.1762 MPa [1.8 kgf/cm2, 26 psi])

      		 0.70 to 4.69 V

      Refrigerant pressure:

      Abnormal (less than 0.1762 MPa [1.8 kgf/cm2, 26 psi])

      		 Below 0.70 V

      Refrigerant pressure:

      Abnormal (more than 3.0254 MPa [30.9 kgf/cm2, 439 psi])

      		 4.69 V or higher

    NG

    REPLACE AIR CONDITIONER PRESSURE SENSOR Click here

    OK

    REPLACE AIR CONDITIONING AMPLIFIER Click here

  12. REPAIR AIR CONDITIONING SYSTEM LEAK


    1. Identify the area where refrigerant leaks Click here.

    2. Repair the identified area of the air conditioning system.

    3. Evacuate the air conditioning system.


    NEXT

    CHARGE REFRIGERANT Click here

  13. INSPECT COOLING FAN SYSTEM


    1. Inspect that the cooling fan operates normally Click here (for 1KR-FE)) Click here (for 1ND-TV)).

      Result
      Result Proceed to
      OK A
      NG (for 1KR-FE) B
      NG (for 1ND-TV) C

    B

    REPAIR COOLING FAN SYSTEM Click here

    C

    REPAIR COOLING FAN SYSTEM Click here

    A

  14. CHARGE REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant Click here.

      Tech Tips

      If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.


    NEXT

  15. RECHECK DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting Lo
      Blower Speed Hi
      A/C Switch On
      Air inlet control Switch Recirculation
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning system operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC. If the DTC is not output after this procedure, it indicates that the cooler dryer in the condenser is not able to absorb moisture in the refrigerant cycle. In this case, to complete the repair it is necessary to replace the cooler dryer.

      OK
      DTC B1423 is not output.

    NG

    REPLACE EXPANSION VALVE Click here

    OK

    REPLACE COOLER DRYER Click here

  16. REPLACE EXPANSION VALVE


    1. Replace the expansion valve with a normal one Click here.

      Tech Tips


      • Replace the expansion valve with a normal one because the expansion valve is either stuck or clogged.


    NEXT

  17. CHARGE REFRIGERANT


    1. Add an appropriate amount of refrigerant Click here.


    NEXT

  18. RECHECK DTC


    1. Recheck for the DTC when the following conditions are satisfied.

      Measurement Condition
      Item Condition
      Engine Speed 2000 rpm
      Vehicle Doors Fully open
      Temperature Setting Lo
      Blower Speed Hi
      A/C Switch On
      Air inlet control Switch Recirculation
      Interior Temperature 25 to 35°C (77 to 95°F)

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. Therefore, it is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning system operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the ambient temperature sensor (thermistor assembly) and the front evaporator temperature sensor (No. 1 cooler thermistor) to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant pressure is not normal after replacing the expansion valve with a normal one, the condenser or pipes may be clogged due to dirt, dust or other contaminants. In this case, clean or replace the condenser or pipes.

      OK
      DTC B1423 is not output.

    NG

    REPLACE CONDENSER Click here

    OK

    END